Field
The present invention relates to electronic power supplies and, more particularly, to switching-mode power supplies with helper current sources.
Background
Many functions of an advanced electronic system, such as a mobile phone, are implemented in a system-on-a-chip (SoC) integrated circuit. The SoC may use several power supplies. The power supplies are generally provided by switching-mode power supplies. The amount of load current for each power supply may be difficult to accurately predict during development of the system. A power supply for the system may designed concurrently with design of the SoC. Inaccuracies in the expected load currents make design of a power supply for the system difficult. If the capability of the power supply is not adequate for the SoC, the system may need to additional expensive components or the power supply may need to be redesigned. Thus, the power supply may be designed to supply currents that are increased by guard-band amounts to allow for inaccuracies in the predicted current loads.
Some prior systems have addressed maximum load current uncertainty by oversizing the switching-mode power supply to provide for any plausible load current. This can increase manufacturing cost, device size, and development cost. Other prior systems have included a helper linear voltage regulator in parallel with the switching-mode power supply to increase the maximum current capability. This can cause performance issues and in such systems it may not be possible to provide dynamically programmable supply voltage.